Between 1995 and 1997, 32 states passed laws requiring insurance carriers to provide minimum postpartum length of stays and a similar federal law went into effect on January 1, 1998. A number of authors have demonstrated that these laws increased average postpartum hospital length of stay, decreased the fraction of mothers and infants discharged 'early', and increased hospitalization costs. There is however limited evidence about the impact of these laws on the health of the mother and her newborn, and estimates from these studies provide conflicting results. In this application, we outline a research program that uses a restricted-use data set of California births to examine the impact of one of these laws. The California Newborns' and Mothers' Health Act of 1997 (NMHA), which went into effect on August 26,1997, mandated that insurance carriers provide coverage for at least a 48 hour hospital stays for normal deliveries and at least a 96 hour hospital stays for cesarean deliveries. The California law is similar to many other state laws and is nearly identical in scope to the federal law that went into effect in 1998. Both the California and federal laws explicitly excluded Medicaid births from coverage. The data for this project will be administrative records of all mothers and newborns discharged from hospitals in California between January 1, 1995 through the end of 2000, merged with the child's state vital statistics (birth and death) records. We have been granted permission to access this data by the state office responsible for data distribution and our research protocol and data safety plan has been approved by both the California State Committee for the Protection of Human Subjects and the University of Maryland. Using an interrupted time series design, we plan to examine the following questions about the California early discharge law: What was the impact of the NMHA on average postpartum length of stay and the fraction of patients discharged early? How does the program's impact vary by patient and hospital characteristics? Were there spillovers to uncovered groups such as Medicaid patients? Did the law improve health outcomes of mothers and their infants? Did the law alter re-admission rates for mothers and infants? Did the law alter neonatal mortality rates? [unreadable] [unreadable] [unreadable]